Yesterday we bought 4months old shihtzu puppy. He is eating and drinking properly but not active at all. Not responding properly. If I am giving him treat he is eating but he is not making an effort from his side to take the treat. Tried taking him for walk but he is sitting in one corner and sometimes shivering. Whenever I hold him he hold me very tightly. No running, no walking. Whenever we leave him, he trues run and hide somewhere. What to do in this case ? Why he is not becoming friendly with us ? It’s so painful seeing him like this.